1. Field of the Invention
This invention relates to motor drive units for use with photographic cameras, and more particularly to improvements in motor drive units having coordinating controls for a camera shutter and an electric motor.
2. Description of the Prior Art
The prior art provides motor drive units for photographic cameras having grips which accommodate the source of power or battery for the electric motor. In addition to the coupling mechanism between the motor drive unit and camera, therefore, there is a need to provide an additional coupling mechanism between the motor drive unit and the grip. The latter extends radially from the motor drive unit. This conventional engaging system leads to complexity in the construction and arrangement of the coupling elements and also to awkward bulkiness of the complete motor driven photographic instrument. What is worse is to move the battery casing in the direction along the length of the grip when an old battery is exchanged for a new one. This causes the operator difficulties in handling the instrument. This characteristic has prejudiced the usefulness of the camera with respect to portability and usefulness for snap photographs.
The prior art motor drive units have other drawbacks. For example, the motor-operating mechanical switch constituting part of the coordinating control system for the shutter and motor-driven film winding mechanisms of the camera must be arranged in the motor drive unit at a restricted location generally near a speed reduction gear train between the motor and the film take-up spool. This arrangement makes it difficult to achieve optimum distribution of the reduction gear train and the power supply control circuit for the motor with the limitation of the overall dimensions. As a result the process for fabricating the various elements of these parts in position with high accuracy cannot be performed economically.
Moreover, when the camera is assembled with the motor drive unit, the camera actuated by an actuator in the motor drive unit. Hence an operator is unable to ready himself for rapid change in attitude of the camera between two different angular positions, for example, lateral and vertical positions. Another problem resides in that the camera is provided with a dust-shielding cover removably received by a recess into which a coupler of the film take-up spool extends to engage a coupler of motor drive unit when unit and camera are assembled with each other. There is some possibility of missing the dust-shielding cover during the time the camera is operated with the motor drive unit because of the lack of the provision for accommodating the removed cover.